include stdint.h for int32_t/uint32_t

Signed-off-by: Jussi Kukkonen <jussi.kukkonen@intel.com>
Reviewed-by: Yong Bakos <ybakos@humanoriented.com>
diff --git a/desktop-shell/shell.h b/desktop-shell/shell.h
index f8f62d5..f73cae5 100644
--- a/desktop-shell/shell.h
+++ b/desktop-shell/shell.h
@@ -24,6 +24,7 @@
  */
 
 #include <stdbool.h>
+#include <stdint.h>
 #include <time.h>
 
 #include "compositor.h"